The Pulfrich Phenomenon: an Objective Signature-Biomarker of MS Pathophysiology (P1.327)

OBJECTIVE: Design an objective method to detect and measure the Pulfrich Phenomenon (PF). BACKGROUND: PF is the illusory perception that an object moving linearly along a 2-D plane appears to instead move in an elliptical 3-D trajectory. Thought to reflect significant inter-eye differences within the visual processing network, PF can provide insight into patient reported visual impairment not otherwise assessed through other methods. DESIGN/METHODS: MS patients with a history of acute optic neuritis (AON) and a control group were asked to indicate whether movement of a pendulum bob followed a 2D linear versus a 3D elliptical object-motion trajectory. In the case of the latter, participants were asked to ascertain the magnitude and direction of the 3D motion, by virtue of the bob’s approximation with respect to one of five colored wires oriented horizontally in close proximity to the bob. Subjects were asked to make the same approximations following monocular application of graduated neutral density filtering (G-NDF). RESULTS: Monocular application of G-NDF to controls resulted in the stereotypic illusion of PF, the magnitude of which intensified and corresponded to increasing levels of filter tinting. Alternately, the application of the G-NDF to AON eyes produced a PF of greater prominence whereas filtering the less affected eyes resulted in attenuation of the PF through consequent neutralization of the interocular brightness disparity brought on by disease. CONCLUSIONS: We have designed a novel, objective method by which to characterize the presence and magnitude of PF in normal subjects (via G-NDF), and MS patients with AON history. Application of G-NDF to the less affected eye in MS patients experiencing PF can be employed to identify the magnitude of filtering necessary to abolish the effect. Furthermore, PF can be employed as a pathophysiologic signature-biomarker for the investigation of changes in visual system architecture and corresponding functional consequences. Disclosure: Dr. Sobhanian has nothing to disclose. Dr. Agarwal has nothing to disclose. Dr. Conger has nothing to disclose. Dr. Conger has nothing to disclose. Dr. Rennaker has nothing to disclose. Dr Balcer received personal compensation from Biogen Idec and consulting for Biogen Idec, Vaccinex and Genzyme. She is on a clinical trial advisory board for Biogen-Idec., Dr. White has nothing to disclose. Dr. Kardon has received personal compensation for activities with Novartis as a consultant. Dr. Beh has received research support from Biogen Idec. Dr. Frohman has received personal compensation for activities with Biogen Idec, Novartis, Acorda Therapeutics, and Questcor. Dr. Frohman has participated in the speakers9 bureau for Teva Neurosciences, Acorda, and Novartis and has received consulting fees from TEVA Neurosciences, and Acorda.,